1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Very hard distribution question!

  1. Mar 31, 2010 #1
    The school psychologist was researching the results of a third school and found them to closely fit a normal distribution with a mean completion time of 20.68 minutes and a standard deviation of 5.3 minutes. Unfortuantly, after he had finished calculating the results, he could not read of of the observed values.

    Given there are 125students at the school, and a percentage error of ten percent determine the possible range of values for the observed frequencies, falling between 14.5 and the 19.5 minute interval.


    z(standardised score) = (x-mean/standard dev)
    Percentage error = |o-e|/total frequency * 100.

    I have no clue.. please help me!
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted